Filter and filter element provided therefor

ABSTRACT

The invention relates to a filter, in particular for fluids polluted by admixtures of water, such as diesel oil, comprising a filter housing ( 1 ) in which at least one filter element ( 9 ) can be received. During the filtering process, fluid can flow through the filter medium ( 11 ) from the outer unfiltered side ( 13 ) of the filter element into an inner filter cavity ( 17 ) forming the filtered side ( 19 ). The filter is characterised in that a water passage ( 39 ) inside a pipe connector ( 35 ) of an end cap ( 23 ) forms a fluid path ( 51 ), which is separated from the other fluid path ( 55 ) that forms the connection between the inner filtered side ( 19 ) of the filter element ( 9 ) and a fluid outlet ( 37 ) of the housing ( 1 ) in the functional position of the filter element ( 9 ). The filter is further characterised in that the element receptacle ( 29 ) forms a through-passage ( 59 ) toward the water collecting chamber ( 31 ), and scaling assemblies ( 83, 87 ) located between the through-passage ( 59 ) and the pipe connection ( 35 ) of the end cap ( 23 ) de-limit a connecting chamber (36) on the outside of the pipe connector ( 35 ). The connecting chamber connects the other fluid path ( 55 ) to the fluid out-let ( 37 ) of the housing ( 1 ).

The invention relates to a filter that is intended in particular for fluids, such as diesel oil, contaminated with water impurities, and that comprises a filter housing in which at least one filter element can be accommodated, through whose filter medium in the filtration process flow can take place from its outer unfiltered side into an inner filter cavity which forms the filtered side, between the unfiltered side and the inner filter cavity there being a water separation device and a separation space for separated water and the filter element on its lower end, which faces the bottom part of the filter housing, being enclosed by an end cap which has a pipe connector as a passage for fluid emerging from the filter cavity which forms the filtered side and a water passage which at least partially surrounds the passage and which is open to the separation space and can be secured on an element retainer of the filter housing which is located above a water collecting space located on the bottom of the filter housing and which forms a fluid outlet which leads out of the housing for fluid emerging from the filtered side. Furthermore, the invention relates to a filter element intended for use in such a fuel filter.

Filters of the aforementioned type are known from the prior art. They are used, for example, in fuel systems for internal combustion engines in order to protect sensitive components, in particular injection systems, against degradation due to the water content entrained in the fuel.

The separation of the water content entrained in the fuel can be effected here by a coagulation process in which on the filter medium water droplets are formed which can flow out of the separation space formed in the filter element to the water collecting space of the filter housing.

In order to ensure the operational reliability of the systems located downstream of the filter, it is critical that in processes of changing the filter element which are necessary over the service life, where the fluid connection between the filtered side of the filter element and the fluid outlet of the housing is interrupted when the end cap of the used filter element is decoupled from the element retainer, there is no contamination of the system by dirt attached to the used filter element falling off.

With respect to this problem, the object of the invention is to provide a filter of the type under consideration whose construction ensures a maximum of operational reliability by the risk of contamination at the fluid outlet of the housing being avoided to the greatest extent possible in changing processes.

This object is achieved according to the invention by a filter having the features specified in claim 1 in its entirety.

Accordingly, an important feature of the invention lies in the fact that the end cap of the filter element is specially designed such that its pipe connector forms separate inner fluid paths both for the cleaned fluid and also for the separated water and can be accommodated in a through channel of the element retainer which is open toward the water collecting space, wherein between the outer side of the pipe connector and the element retainer, active seal arrangements delimit a connecting space via which the filtered-side inner filter cavity is connected to the fluid outlet of the housing in the operating position of the filter element.

In this construction, when a used filter element is removed from the element retainer, a continuous opening is formed so that dirt falling off the filter element falls past the filtered-side fluid outlet of the housing into the water collecting space.

An additional further advantage of the invention lies in the fact that for a filter element accommodated in the filter housing, the seal arrangements which are active between the through channel of the element retainer and the pipe connector of the end cap also effect sealing between the unfiltered side of the filter housing and the filtered side. Thus it is unnecessary to provide a seal arrangement relative to the inside of the housing on the outer periphery of the pertinent end cap of the filter element, as is conventional in the prior art, but instead sealing is effected with a much smaller seal diameter, as a result of which reduced mounting forces and thus simplification result in the installation and removal of filter elements.

In especially advantageous exemplary embodiments for forming the fluid path between the filtered side and the fluid outlet within the pipe connector, the end cap has an inner pipe body which extends with its inlet end into the filter cavity which forms the filtered side and is open on one outlet end to the connecting space which is located on the outside of the pipe connector.

For forming the other inner fluid path, the pipe connector of the end cap has a free lower end which is open to the water collecting space, wherein between the outside of the inner pipe body and the inside of the pipe connector, a free space forms this fluid path from the separation space to the water collecting space.

In especially advantageous exemplary embodiments, the arrangement can be designed such that the pipe connector and the inner pipe body with their ends facing the interior of the filter element form respective concentric connecting rings, of which the outer ring projects into the separation space and on the outside adjoins the support tube of the filter medium and the inner ring projects into the inner filter cavity and on the outside adjoins the inside of a hydrophobic screen which forms part of the water separation device and which surrounds the filtered side.

Advantageously, the seal arrangements between the pipe connector of the end cap and through channel of the element retainer can in each instance be formed by O-rings which sit in the annular grooves of the pipe connector.

In an especially advantageous manner, the arrangement here can be made such that an O-ring for sealing between the outlet end of the inner pipe body belonging to the filtered side and the water collecting space is located near the lower free end of the pipe connector and an O-ring for sealing between the top of the intermediate bottom of the element retainer, which top belongs to the unfiltered side, and the filtered side on the pipe connector is located above the outlet end of the inner pipe body.

With respect to the configuration of the inner pipe body in the pipe connector of the end cap, the arrangement can be designed such that the inner pipe body is shaped as a T-pipe, the axially extending inlet part which discharges on the inner connecting ring passing into a transverse channel which forms two outlet ends which discharge on the outside of the pipe connector at two opposing points. The filter element can thus assume more than one rotational position in its operating position.

According to claim 8, the subject matter of the invention is also a filter element intended for use in such a filter according to the invention.

The invention is detailed below using one exemplary embodiment shown in the drawings.

FIG. 1 shows a longitudinal section of a fuel filter provided with a water separation device according to the prior art;

FIG. 2 shows a longitudinal section of a filter according to the exemplary embodiment of the invention to be described here;

FIG. 3 shows a longitudinal section corresponding to FIG. 2, the exemplary embodiment being shown turned by 90° relative to FIG. 2;

FIG. 4 shows a perspective oblique view of only one filter element end cap of the exemplary embodiment of the invention, which view is drawn enlarged and cut in half compared to FIGS. 1 to 3;

FIG. 5 shows a representation corresponding to FIG. 4, the end cap, however, in contrast being turned by 90°, and

FIG. 6 shows a plan view of the end cap, the rotary position shown in FIG. 5 being illustrated.

The invention is explained below using the example of a fuel filter which is designed to clean diesel oil in a fuel supply system (not shown) of an internal combustion engine, which diesel oil is contaminated with certain water impurities. The invention is equally well suited for other types of fluids.

The device has a filter housing 1 with a hollow cylindrical main part 3 and a bottom part 5 which adjoins its underside. On the upper end, a housing cover 7, which can be removed for installation and removal of a filter element 9, is screwed to the main part 3. Between the outside of the filter medium 11 of the filter element 9 held in the housing 1, which medium is formed by a filter mat, and the inside wall of the housing 1, there is an intermediate space which in the filtration process forms the unfiltered side 13. The fuel to be cleaned can be supplied to the unfiltered side 13 via an inlet opening 15 and flows through the filter element 9 from the outside to the inside to an inner filter cavity 17 which, in the filtration process, forms the filtered side 19.

In the manner which is conventional in filter elements, on the ends, there are end caps 21 and 23 which form enclosures for the filter medium 11 and a fluid-permeable support tube 25 which rests against the interior of said filter medium. At a radial distance from the support tube 25, there is a hydrophobic screen 26 which surrounds the inner filter cavity 17 in the form of a tube. In order to effect water separation, such fuel filters use a filter medium 11 that acts by coagulation for the water entrained by the fuel, so that water precipitates in droplet form and remains in the intermediate space between support tube 25 and hydrophobic screen 26 and sinks since the screen 26 is impermeable to coagulated water droplets. The intermediate space therefore forms a water separation space 27 in which the separated water sinks toward the end cap 23.

With this lower end cap 23, the filter element 9 is secured on a housing-mounting element retainer 29 which is located above the bottom part 5 and forms a water collecting space 31 from which separated water can be discharged via a water drain 33. For the interaction with the element retainer 29, the end cap 23 in the device corresponding to the prior art has a central pipe connector 35 as a passage for the cleaned fuel which emerges from the filtered side 19, i.e., the inner filter cavity 17, and which travels to a fuel outlet 37 located in the element retainer 29 and from there to the outside of the housing 1. For the outflow of the separated water located in the separation space 27, in the end cap 23, a water passage 39 is formed which is open to the separation space 27, which surrounds the pipe connector 35, and via which the separated water travels directly along the outside of the element retainer 29 to the water collecting space 31. The corresponding flow conditions are illustrated in FIG. 1 by flow arrows, of which the arrows 41 illustrate the fuel inflow to the unfiltered side 13, the arrows 43 depict the flow of the cleaned diesel oil, and the arrows 45 show the water flow. For sealing of the unfiltered side 13, which is located on the outside of the filter element 9 relative to the bottom-side water collecting space 31, there is a seal arrangement in the form of a gasket 47 which seals against the inside of the filter housing on the outer periphery of the end cap 23.

The exemplary embodiment of the device according to the invention, which is explained using FIGS. 2 to 6, conversely differs mainly by a special configuration of the end cap 23 assigned to the element retainer 29 and the special construction of the element retainer 29 which is adapted to it. While in the prior art the water passage 39 on the bottom of the separation space 27 is directly connected to the water collecting space 31 so that the separated water, see arrows 45 from FIG. 1, drains along the outside of the element retainer 29 to the collecting space 31, in the present invention, the pipe connector 35 of the end cap 23 forms not only a fluid path 55 for the discharge of cleaned fuel from of the filtered side 19 of the filter element 9 and toward the fuel outlet 37, but the pipe connector 35, in addition to this fluid path 55, also forms another inner fluid path 51 that is separate from the latter and which leads from the separation space 27 via the free lower end 53 of the pipe connector 35 to the water collecting space 31. This configuration of the fluid paths 51 for water and of an inner fluid path 55 that is separate therefrom between the filtered side 19 and the fuel outlet 37 makes it possible to provide the element retainer 29 on an intermediate bottom 57 which forms a central through channel 59 to the bottom-side water collecting space 31. The sealing device, which during the filtration process separates the unfiltered side 13 from the water collecting space 31, therefore need not be provided on the peripheral edge of the end cap 23, but can be provided between the pipe connector 35 and the element retainer 29 on the central through channel 59, that is, with an advantageously small seal diameter.

FIGS. 2 and 3 show different positions of the filter housing 1, in FIG. 2, the inner fluid path 51 of the pipe connector 35 of the end cap 23, which forms the drain path for discharge of the separated water from the separation space 27 to the water collecting space 31, being clearly visible. In the representation of FIG. 3, which in contrast has been turned by 90°, the other fluid path 55, via which cleaned fuel emerging from the filtered side 19 of the inner cavity 17 of the filter element 9 flows to the fuel outlet 37 and from there emerges from the housing via an outlet 61, is more clearly apparent.

FIGS. 4 to 6 show greater detail of the configuration of the end cap 23. As is conventional in such end caps, it is a one-piece injection molded part of plastic material with a peripheral edge 65 which forms an outer enclosure of the filter element 9 and which projects out of a round, planar bottom surface 63. The central pipe connector 35 extends from the underside of the bottom surface 63 and on the top side of the bottom surface 63 undergoes transition into a connecting ring 67 which projects toward the top and which has a somewhat greater diameter than the pipe connector 35 located on the underside. Within the connecting ring 67, and concentric to it, there is a second connecting ring 69 which projects up over the plane of the bottom surface 63. This ring forms the inlet end 71 of an inner pipe body 73 which is located within the pipe connector 35. This pipe body 73 forms the inner fluid path 55 which is provided in the end cap 23 for the connection between the filtered side 19 and the fuel outlet 37. As FIGS. 2 and 3 show, the inner connecting ring 69 extends into the filter cavity 17 which forms the filtered side 19, with the ring 69 on the outside adjoining the inside of the hydrophobic screen 26. The outer connecting ring 67 projects into the separation space 27 and on the outside adjoins the support tube 25 of the filter medium 11. As is most apparent from FIG. 4, along the inside of the ring 67 and along the outside of the inner pipe body 73, the fluid path 51 for the separated water that emerges on the lower end 53 of the pipe connector 35 is formed. The representation of FIG. 5, which by contrast has been turned by 90°, shows the fluid path 55 more clearly for the cleaned fuel which enters the pipe body 73 via the inlet end 71 and passes via an axially extending inlet part 75 in the form of a T-pipe into a transverse channel 77 which forms two outlet ends 79 from which the fuel travels to the fuel outlet 37.

On the outer periphery of the pipe connector 35 between the outlet ends 79 and the bottom surface 63, there is an annular groove 81 for an O-ring 83 for sealing between the top side of the intermediate bottom 57 of the element retainer 29, which top side belongs to the unfiltered side 13, and the filtered side 19. An annular groove 85 which is adjacent to the lower free end 53 forms the seat for an O-ring 87 for sealing between the outlet ends 79 of the pipe body 73, which belong to the filtered side 13, and the water collecting space 31. As is apparent from FIG. 2, between the O-rings 85, 87, between the outside of the pipe connector 35 and the inside of the through channel 59, a correcting space 36 is formed via which the cleaned fuel travels from the outlet ends 79 to the outlet 37 of the housing 1. 

1. A filter that is intended in particular for fluids, such as diesel oil, contaminated with water impurities, and that comprises a filter housing (1) in which at least one filter element (9) can be accommodated, through whose filter medium (11) in the filtration process flow can take place from its outer unfiltered side (13) into an inner filter cavity (17) which forms the filtered side (19), between the unfiltered side (13) and the inner filter cavity (17) there being a water separation device (26) and a separation space (27) for separated water and the filter element (9) on its lower end which faces the bottom part (5) of the filter housing (1) being enclosed by an end cap (23) which has a pipe connector (35) as a passage for fluid emerging from the filter cavity (17) which forms the filtered side (19) and a water passage (39) which at least partially surrounds the passage and which is open to the separation space (27) and can be secured on an element retainer (29) of the filter housing (1) which is located above a water collecting space (31) located on the bottom of the filter housing (1) and which forms a fluid outlet (37) which leads out of the housing (1) for fluid emerging from the filtered side (19), characterized in that the water passage (39) within the pipe connector (35) of the end cap (23) forms a fluid path (51) that is separate from the other fluid path (55) which forms the connection between the inner filtered side (19) of the filter element (9) and the fluid outlet (37) of the housing (1) in the operating position of the filter element (9), that the element retainer (29) forms a through channel (59) to the water collecting space (31), and that seal arrangements (83, 87) which are located between the through channel (59) and the pipe connector (35) of the end cap (23) on the outside of the pipe connector (35) form a connecting space (36) which connects the other fluid path (55) to the fluid outlet (37) of the housing (1).
 2. The filter according to claim 1, characterized in that the end cap (23) for forming the fluid path (55) between the filtered side (19) and the fluid outlet (37) within the pipe connector (35) has an inner pipe body (73) which extends with its inlet end (71) into the filter cavity (17) which forms the filtered side (19) and is open on one outlet end (79) to the connecting space (36) which is located on the outside of the pipe connector (35).
 3. The filter according to claim 1, characterized in that the pipe connector (35) of the end cap (23) has a free lower end (53) which is open to the water collecting space (31) and that between the outside of the inner pipe body (73) and the inside of the pipe connector (35) a free space forms the fluid path (51) from the separation space (27) to the water collecting space (31).
 4. The filter according to claim 1, characterized in that the pipe connector (35) and the inner pipe body (73) with their ends facing the interior (17) of the filter element (9) form respective concentric connecting rings (67, 69), of which the outer ring (67) projects into the separation space (31) and on the outside adjoins the support tube (25) of the filter medium (11) and the inner ring (69) projects into the inner filter cavity (17) and on the outside adjoins the inside of a hydrophobic screen (26) which forms part of the water separation device and which surrounds the filtered side (19).
 5. The filter according to claim 1, characterized in that the seal arrangements between pipe connector (35) of the end cap (23) and through channel (59) of the element retainer (29) are in each instance formed by O-rings (83, 87) which sit in annular grooves (81, 85) of the pipe connector (35).
 6. The filter according to claim 1, characterized in that an O-ring (87) for sealing between the outlet end (79) of the inner pipe body (73) belonging to the filtered side (19) and the water collecting space (31) is located near the lower free end (53) of the pipe connector (35) and an O-ring (83) for sealing between the top side of the intermediate bottom (57) of the element retainer (29), which top side belongs to the unfiltered side (13), and the filtered side (19) on the pipe connector (35) is located above the outlet end (79) of the inner pipe body (73).
 7. The filter according to claim 1, characterized in that the inner pipe body (73) is shaped in the manner of a T-pipe, the axially extending inlet part (75) which discharges on the inner connecting ring (69) passing into a transverse channel (77) which forms two outlet ends (79) which discharge on the outside of the pipe connector (35) at two opposing points into the connecting space (36).
 8. A filter element (9) intended for use in a filter according to claim 1, with a filter medium (11) through which flow takes place for a filtration process from its outer unfiltered side (13) into an inner filter cavity (17) which forms the filtered side (19), between the unfiltered ‘side (13) and inner filter cavity (17) there being a water separation device (26) and a separation space (27) for separated water and the filter element (9) on its lower end which faces the bottom part (5) of the filter housing (1) being enclosed by an end cap (23) which has a pipe connector (35) and which can be secured on an element retainer (29) of the filter housing (1) which is located above a water collecting space (31) located on the bottom of the filter housing (1) and forms a fluid outlet (37) which leads out of the housing (1) for fluid emerging from the filtered side (19), characterized in that in the pipe connector (35) of the end cap (23) separate fluid paths (55, 51) are made, of which in the operating position of the filter element (9) one (55) forms the connection between the inner filtered side (19) of the filter element (9) and the fluid outlet (37) of the housing (1) and the other fluid path (51) forms the connection from the separation space (27) of the filter element (9) to the water collecting space (31). 